Adjustable Trid

Implementation of the adjustable bi-fidelity Trid function as defined in:

Toal, D.J.J. Some considerations regarding the use of multi- fidelity Kriging in the construction of surrogate models. Struct Multidisc Optim 51, 1223–1245 (2015) doi:10.1007/s00158-014-1209-5

\[f_h(x_1, ..., x_{10}) = \sum^{10}_{i=1} (x_i - 1)^2 - \sum^{10}_{i=2} x_ix_{i-1}\]

\[f_l(x_1, ..., x_{10}) = \sum^{10}_{i=1} (x_i - a)^2 - (a - 0.65) \sum^{10}_{i=2} x_ix_{i-1}\]

where \(a \in [0, 1]\) is the adjustable parameter

adjustable_trid_lf(xx, a)

trid_hf(xx)